One solution for keeping a medicament delivery device as pre-assembled as possible is to deliver the medicament delivery device with a delivery member, such as a needle, pre-attached. This solution often causes the rear end of the needle to protrude into the interior of the container, which could be a drawback if the medicament reacts with the material of the delivery member when exposed for a period of time. In that respect it would be desirable to have the rear part of the delivery member outside the container until the delivery is to be performed. To minimize the number of actions needed in order to perform the injection, some devices only need to be pressed against the injection area, without the need of injecting by pressing a button or the like, which causes the needle to penetrate the injection area and the device perform the injection. Thereby, the delivery procedure is reduced by at least one step.
One such device is disclosed in patent document EP 1349590 B describing an injector having a number of features that facilitate the handling of the injector. The penetration and injection is performed manually by simply pressing the proximal end of a needle shield against the delivery area, causing the shield to move in a distal direction, enabling the needle to penetrate the injection area and thereafter initialize the injection process. When the injection is performed the injector is withdrawn whereby the needle shield extracts around the needle in a locked way.
However, a disadvantage of prior art solutions is that they sometimes are unreliable and may unintentionally be actuated, either by mishap or by improper usage. Thus, as can be noted, human handling aspects of the medicament delivery device are crucial and there are several rationales for improving existing solutions. One important safety aspect when handling a medicament delivery device is the locking of the injection actuator, before the medicament delivery device is ready for use. In U.S. Pat. No. 6,893,420 is disclosed a device arranged with a locking means for locking a latch that prevents the automatic penetration and injection means from being released before mixing of the medicament is finished. However this device suffers from the disadvantage of a user having to remove the locking means actively from the device after the mixing is finished, thereby causing an unnecessary step which may be disadvantageous, especially considering emergency usage of said devices. There is therefore a need for an arrangement that can provide improved safety handling, as well as improved medicament handling, i.e. arrangements where the medicament can be delivered with pre-assembled devices but still remain in storage, without having the medicament compromised or degraded due to the medicament reacting with the material of the delivery member when exposed for a period of time and at the same time being reliable, safe and intuitive to use.